<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="js/jquery-3.3.1.js"></script>
    <script>
        $(f);

        function f(){
            $("#wd").focus(function(){
                $(this).val("");
            });
        }
    </script>
</head>
<body>
    <input id="wd" value="电风扇" />
</body>
</html>